1. Field of the Invention
The present invention relates to an apparatus for evaluating a defect or the like on, e.g., a semiconductor wafer. A defect means a defect, a foreign substance, a flaw, a particle, or unevenness.
2. Related Background Art
In a conventional apparatus for evaluating a defect in an object such as a semiconductor wafer, a laser beam is irradiated on the object obliquely with respect to the surface of an object to observe scattered light from a defect inside the object is observed from the object surface side in a direction different from the laser beam incident direction, thereby detecting a defect or a particle in the object (Japanese Patent Application Laid-Open No. 4-24541). In this apparatus, the scattered light is observed in a direction different from the direction of the laser beam reflected by the object, thereby minimizing the influence of reflected light. Also, the wavelength of laser beam or the object temperature can be changed to adjust the depth in the object to which the laser beam travels.
In this apparatus, however, when a defect near the surface of the object is observed, a flaw or the like on the surface is observed together in the same observation field. Since the defect cannot be discriminated from the flaw, accurate evaluation cannot be obtained.
To solve this problem, in a conventional defect evaluation apparatus comprising a laser irradiation means for obliquely irradiating a laser beam onto the observation surface of an object, and an observation means for observing, through the observation surface, scattered light which is generated by a defect or a particle in the object when refracted light of the laser beam becomes incident thereon, a component discrimination means is used to allow observation with both light mainly containing a p-polarized light component and light mainly containing an s-polarized light component. With this apparatus, even when a defect near the surface of the object surface is to be observed, and a flaw or the like on the surface is present in the same observation field, the defect can be discriminated from the flaw, so accurate evaluation can be obtained.
However, the shape information of the defect cannot be obtained.